cling: cleanup, fix runtime error

[wegank]

Description of changes

Follows #284865.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[wegank]

Result of nixpkgs-review pr 302749 run on aarch64-darwin 1

2 packages built:

• cling
• xeus-cling

[thomasjm]

Looks good to me, thanks for cleaning up!

I'm a little surprised that it's working with useLLVMLibcxx on Darwin. Did you try executing some code? FWIW I like to run the following as a smoke check:

#include <iostream>
std::cout << "hi" << std::endl;

[wegank]

Just ran the above on aarch64-darwin:

$ result/bin/cling

****************** CLING ******************
* Type C++ code and press enter to run it *
*             Type .q to exit             *
*******************************************
[cling]$ #include <iostream>
[cling]$ std::cout << "hi" << std::endl;
hi
[cling]$ .q